diff options
Diffstat (limited to 'drivers/irqchip/irq-riscv-intc.c')
| -rw-r--r-- | drivers/irqchip/irq-riscv-intc.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c new file mode 100644 index 0000000000..e8d01b14cc --- /dev/null +++ b/drivers/irqchip/irq-riscv-intc.c @@ -0,0 +1,204 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2012 Regents of the University of California + * Copyright (C) 2017-2018 SiFive + * Copyright (C) 2020 Western Digital Corporation or its affiliates. + */ + +#define pr_fmt(fmt) "riscv-intc: " fmt +#include <linux/acpi.h> +#include <linux/atomic.h> +#include <linux/bits.h> +#include <linux/cpu.h> +#include <linux/irq.h> +#include <linux/irqchip.h> +#include <linux/irqdomain.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/smp.h> + +static struct irq_domain *intc_domain; + +static asmlinkage void riscv_intc_irq(struct pt_regs *regs) +{ + unsigned long cause = regs->cause & ~CAUSE_IRQ_FLAG; + + if (unlikely(cause >= BITS_PER_LONG)) + panic("unexpected interrupt cause"); + + generic_handle_domain_irq(intc_domain, cause); +} + +/* + * On RISC-V systems local interrupts are masked or unmasked by writing + * the SIE (Supervisor Interrupt Enable) CSR. As CSRs can only be written + * on the local hart, these functions can only be called on the hart that + * corresponds to the IRQ chip. + */ + +static void riscv_intc_irq_mask(struct irq_data *d) +{ + csr_clear(CSR_IE, BIT(d->hwirq)); +} + +static void riscv_intc_irq_unmask(struct irq_data *d) +{ + csr_set(CSR_IE, BIT(d->hwirq)); +} + +static void riscv_intc_irq_eoi(struct irq_data *d) +{ + /* + * The RISC-V INTC driver uses handle_percpu_devid_irq() flow + * for the per-HART local interrupts and child irqchip drivers + * (such as PLIC, SBI IPI, CLINT, APLIC, IMSIC, etc) implement + * chained handlers for the per-HART local interrupts. + * + * In the absence of irq_eoi(), the chained_irq_enter() and + * chained_irq_exit() functions (used by child irqchip drivers) + * will do unnecessary mask/unmask of per-HART local interrupts + * at the time of handling interrupts. To avoid this, we provide + * an empty irq_eoi() callback for RISC-V INTC irqchip. + */ +} + +static struct irq_chip riscv_intc_chip = { + .name = "RISC-V INTC", + .irq_mask = riscv_intc_irq_mask, + .irq_unmask = riscv_intc_irq_unmask, + .irq_eoi = riscv_intc_irq_eoi, +}; + +static int riscv_intc_domain_map(struct irq_domain *d, unsigned int irq, + irq_hw_number_t hwirq) +{ + irq_set_percpu_devid(irq); + irq_domain_set_info(d, irq, hwirq, &riscv_intc_chip, d->host_data, + handle_percpu_devid_irq, NULL, NULL); + + return 0; +} + +static int riscv_intc_domain_alloc(struct irq_domain *domain, + unsigned int virq, unsigned int nr_irqs, + void *arg) +{ + int i, ret; + irq_hw_number_t hwirq; + unsigned int type = IRQ_TYPE_NONE; + struct irq_fwspec *fwspec = arg; + + ret = irq_domain_translate_onecell(domain, fwspec, &hwirq, &type); + if (ret) + return ret; + + for (i = 0; i < nr_irqs; i++) { + ret = riscv_intc_domain_map(domain, virq + i, hwirq + i); + if (ret) + return ret; + } + + return 0; +} + +static const struct irq_domain_ops riscv_intc_domain_ops = { + .map = riscv_intc_domain_map, + .xlate = irq_domain_xlate_onecell, + .alloc = riscv_intc_domain_alloc +}; + +static struct fwnode_handle *riscv_intc_hwnode(void) +{ + return intc_domain->fwnode; +} + +static int __init riscv_intc_init_common(struct fwnode_handle *fn) +{ + int rc; + + intc_domain = irq_domain_create_linear(fn, BITS_PER_LONG, + &riscv_intc_domain_ops, NULL); + if (!intc_domain) { + pr_err("unable to add IRQ domain\n"); + return -ENXIO; + } + + rc = set_handle_irq(&riscv_intc_irq); + if (rc) { + pr_err("failed to set irq handler\n"); + return rc; + } + + riscv_set_intc_hwnode_fn(riscv_intc_hwnode); + + pr_info("%d local interrupts mapped\n", BITS_PER_LONG); + + return 0; +} + +static int __init riscv_intc_init(struct device_node *node, + struct device_node *parent) +{ + int rc; + unsigned long hartid; + + rc = riscv_of_parent_hartid(node, &hartid); + if (rc < 0) { + pr_warn("unable to find hart id for %pOF\n", node); + return 0; + } + + /* + * The DT will have one INTC DT node under each CPU (or HART) + * DT node so riscv_intc_init() function will be called once + * for each INTC DT node. We only need to do INTC initialization + * for the INTC DT node belonging to boot CPU (or boot HART). + */ + if (riscv_hartid_to_cpuid(hartid) != smp_processor_id()) { + /* + * The INTC nodes of each CPU are suppliers for downstream + * interrupt controllers (such as PLIC, IMSIC and APLIC + * direct-mode) so we should mark an INTC node as initialized + * if we are not creating IRQ domain for it. + */ + fwnode_dev_initialized(of_fwnode_handle(node), true); + return 0; + } + + return riscv_intc_init_common(of_node_to_fwnode(node)); +} + +IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init); + +#ifdef CONFIG_ACPI + +static int __init riscv_intc_acpi_init(union acpi_subtable_headers *header, + const unsigned long end) +{ + struct fwnode_handle *fn; + struct acpi_madt_rintc *rintc; + + rintc = (struct acpi_madt_rintc *)header; + + /* + * The ACPI MADT will have one INTC for each CPU (or HART) + * so riscv_intc_acpi_init() function will be called once + * for each INTC. We only do INTC initialization + * for the INTC belonging to the boot CPU (or boot HART). + */ + if (riscv_hartid_to_cpuid(rintc->hart_id) != smp_processor_id()) + return 0; + + fn = irq_domain_alloc_named_fwnode("RISCV-INTC"); + if (!fn) { + pr_err("unable to allocate INTC FW node\n"); + return -ENOMEM; + } + + return riscv_intc_init_common(fn); +} + +IRQCHIP_ACPI_DECLARE(riscv_intc, ACPI_MADT_TYPE_RINTC, NULL, + ACPI_MADT_RINTC_VERSION_V1, riscv_intc_acpi_init); +#endif |